Offshore hydrocarbon producing operations typically require the installation of subsea pipelines to transport the produced hydrocarbons from one location to another. In many situations, installation of a subsea pipeline requires that the ends of two unconnected sections of pipeline disposed adjacent the ocean floor must be connected by a specially fabricated spool piece which can only be fabricated by knowing the exact distance and angular orientation between the ends of the unconnected sections. Typically, these distance and angular orientation measurements are obtained by utilizing the services of a diver, or a manned submarine or diving bell.
Water depths of interest to the offshore petroleum industry have now increased to the point where use of a diver or a manned submarine or diving bell is either prohibitively expensive or impractical. Further, in deep waters the hazards associated with manned subsea operations may be excessive. Accordingly, the need exists for a remotely operable method and apparatus for determining the distance and angular orientation between two structurally unconnected members disposed adjacent the ocean floor, which do not require manned subsea operations and which are efficient and economical to use. The present invention satisfies this need.